This sheet is a generic summary, designed to give the reader a basic level of background information about the substance in question. Great care has been taken to represent as effectively and correctly as possible the broad range of (not necessarily consistent) information which is available from a variety of sources. The reader must accept therefore that this sheet has no legal status and cannot be relied upon in any legal proceedings. SEPA disclaims any responsibility or liability whatsoever for errors and omissions in this sheet.

What is it?

Under normal conditions, pure Dieldrin is white crystals, which have a faint chemical smell. It often contains impurities, which give it a beige colour and possibly also a stronger smell. Dieldrin evaporates easily. In its pure form, it melts at 176 degrees celsius, but impure forms have a lower melting point of around 95 degrees celsius. Dieldrin does not dissolve in water, but readily mixes with organic (carbon-containing) solvents, fats and oils. Dieldrin is part of the "drin" group of pesticides and therefore has similar properties to other members of the group such as Endrin, Aldrin and Isodrin.

What is it used for?

In the past, Dieldrin was widely used as a pesticide to control insects in soils and also to control insects carrying disease (such as malarial mosquitoes). Its use has now been banned in many countries (including the UK). It may however still be used in some developing countries - mainly as an agricultural pesticide, but also to control pests in wood and textiles.

Where does it come from?

In countries where it is still used, releases of Dieldrin occur as a result of its manufacture, transport and use as a pesticide. It is also formed when the chemically similar Aldrin is broken down in the environment. There are not thought to be any natural sources of Dieldrin to the environment.

How might it affect the environment?

Dieldrin is highly toxic to aquatic organisms and many other forms of wildlife and can accumulate in the environment, particularly in the fat of animals. Dieldrin binds strongly to soil particles and is not easily broken down. Little seeps to groundwaters. That which evaporates from soils into the atmosphere may travel considerable distances before being re-deposited elsewhere. Dieldrin is classed as a "persistent organic pollutant" (POP). The effects of Dieldrin pollution cause concern at a global as well as local level.

How might exposure to it affect human health?

Dieldrin can enter the body inhalation of air containing dieldrin, ingestion of contaminated water or food or by dermal contact with dieldrin. Exposure to dieldrin occurs mainly by ingestion of contaminated food. Inhalation of moderate levels of dieldrin over long periods of time can cause a range of adverse health effects including headaches, dizziness, uncontrollable muscle movements irritability, and vomiting. Exposure to high levels can cause convulsions and kidney damage. Ingestion of dieldrin can cause nausea vomiting and diarrhoea. Ingestion of large quantities of dieldrin can result in symptoms similar to those for inhalation and in extreme cases death. Dermal contact with high levels of dieldrin can cause skin irritation. Aldrin converts to dieldrin once inside the body therefore exposure to aldrin can also result in elevated dieldrin levels in the body. The International Agency for Research on Cancer has designated dieldrin as being not classifiable as to its carcinogenicity to humans. However, exposure to dieldrin at normal background levels is unlikely to have any adverse effect on human health.

What steps are being taken to limit the potential impacts?

Dieldrin is a UK Red List pollutant because of concern about its harmful impacts on the environment and human health. Releases of Dieldrin are controlled through the Food and Environmental Protection Act (FEPA 1985) and the Control of Pesticides Regulations (COPR 1986). Its use is now banned in the EU. European Directives regulating levels of Dieldrin include that concerned with the marketing and use of certain dangerous chemicals (79/117/EEC) and that concerned with pollution of the aquatic environment (76/464/EEC). At an international level, Dieldrin is the subject of two proposed UN treaties, is banned under the UNECE POPs protocol and proposed for elimination under the UNEP POPs Convention. Dieldrin is also listed as a candidate substance under the OSPAR Convention which protects the marine environment of the north-east Atlantic Ocean.